A police sergeant at Scotland Yard's specially trained riot squad today denied assaulting a woman at the G20 protests near the Bank of England.

The Territorial Support Group (TSG) sergeant, Delroy Smellie, 47, is accused of striking an activist during a vigil on 2 April for Ian Tomlinson, the newspaper vendor who died at the protests the previous day.

Appearing briefly in the dock at City of Westminster magistrates court in London today, Smellie spoke only to confirm his name and address and deny the charge of common assault.

A video of the incident near the Bank of England, in which he allegedly struck Nicola Fisher, was posted on YouTube and handed to the Guardian. Fisher, from Brighton, was among a large crowd who attended a vigil for Tomlinson, who collapsed and died after being struck by an officer from the TSG.

Smellie, based at the Larkhall Lane branch of the TSG in Clapham, is the first officer to face a charge in relation to the G20 protests. Requesting a four-day trial yesterday, prosecutor Nicholas Paul said the crown could present 23 witnesses. "Obviously a lot of people were present," he said. "But a lot of this can be dealt with by photographs and what has become the infamous DVD footage."

District Judge Daphne Wickham told Smellie he was granted unconditional bail until his trial, scheduled for Monday 22 March next year at the same courthouse.